Aroma-active Components Research Articles

Characterization of the aroma in barley leaves from different cultivars and tillering stages by HS-SPME/GC-MS, GC-O and E-nose

Barley leaf, as a food source with medicinal attributes, is an excellent raw material for functional food. Aroma-active compounds that characterize the unique flavor of the barely leaf is an important issue that should be clarified. Therefore, gas chromatography-mass spectrometry (GC-MS) combined with GC-olfactometry (GC-O) were employed to investigate the volatiles in barely leaves from 7 cultivars and 2 tillering stages. According to a quantitative study and odor activity value (OAV), 18 volatile compounds were identified as aroma-active components. Aldehydes and alcohols are the dominant compounds. Hexanal, 2-hexenal, and isovaleraldehyde are the most abundant compounds in the former. (E)-3-hexen-1-ol, hexanol, 1-pentene-3-ol, (E)-2-hexenol, linalool and (Z)-2-pentenol are the main aromatic active compounds in the latter. The impact of the tillering stage was more significant than that of cultivars on the characteristics of volatile compounds. Furthermore, through the multivariate statistical analysis, it was found that 9 volatile compounds with Variable Importance in Projection (VIP)≥1, including (E)-2-hexenol, (E)-3-hexene-1-ol, (Z)-2-pentenol, 2-octanone, pentadecanal, 1-penten-3-ol, linalool, 2-hexenal and hexanol, played a significant role in differentiating samples. Consistent results were also got from the quantitative descriptive analysis (QDA) and electronic nose (E-nose) measurement. Overall, it is suggested that Flower 30 and Morex are the most suitable specialized cultivars to produce barley leaf products.

Characterization of Volatile Flavor Compounds and Aroma Active Components in Button Mushroom (Agaricus bisporus) across Various Cooking Methods.

To investigate the impact of various cooking methods on the volatile aroma compounds of button mushroom, gas chromatography-mass spectrometry (GC-MS) and electronic nose (E-nose) were utilized for aroma analysis. The results indicated that the E-nose was able to effectively distinguish between the samples prepared using different cooking methods. In the raw, steamed, boiled and baked samples, 37, 23, 33 and 35 volatiles were detected, respectively. The roasting process significantly contributed to the production of flavor compounds, giving button mushroom its distinctive flavor. Sixteen differential aromas were identified based on the p-value and VIP value. Additionally, the cluster analysis of differential aroma substances revealed a stronger odor similarity between the steamed and raw groups, consistent with the results of the OPLS-DA analysis of overall aroma components. Seven key aromas were identified through OAV analysis and omission experiments. In addition, 1-octen-3-one was identified as the main aroma component of cooked button mushroom. The findings of the study can be valuable for enhancing the flavor of cooked button mushroom.

Characteristic aroma-active components of fried green onion (Allium fistulosum L.) through flavoromics analysis.

Green onion (Allium fistulosumL.) is a perennial herb with a characteristic allium aroma. Meanwhile, fried green onion oil has a rich flavor that is popular in traditional Chinese cuisine. In this work, the key aroma components of fried green onion oil were focused via flavoromics analysis. The oil samples had a low score of a green aroma but a high score of salty, greasy aromas. Whereafter, a total of 36 aroma-active substances with flavor dilution (FD) factors ranging from 1 to 6561 were identified in fried green onion oil, while 42 were detected in fried green onion residue with FD factors ranging from 1 to 19683. Additionally, the recombination and omission tests revealed that furaneol, dimethyl trisulfide, allyl methyl trisulfide, (E,E)-2,4-decadienal, etc., were the key aroma compounds in fried green onion oil. Furthermore, the observation of the reaction of thioethers at high temperatures revealed that dimethyl disulfide undergoes polymerization to form dimethyl trisulfide. The research results can provide a theoretical basis for the standardization and industrial production of Chinese cuisine.

Formation of key aroma-active and off-flavor components in concentrated peach puree

Non-volatiles offer some insight into the formation of aroma-active components in peach puree (PP), but more depth investigation is still needed. Formation pathways of key aroma-active and off-flavor components in PP during thermal concentration (PP + C) and sterilization (PP + C + S) are unclear. Therefore, GC-O-MS combined with UPLC-MS/MS was used to identify the volatile and nonvolatile components and their formation pathways. Among the 36 aroma-active compounds, the contents of γ-decalactone, hexyl acetate, leaf acetate, hexanal, and 1-hexanol (odor activity value ≥ 1) decreased by 46 %, 100 %, 100 %, 92 %, and 100 % between PP and PP + C + S, causing the weakening of “green” and “fruity” attributes. Off-flavor components including 1-octen-3-one, isobutyric acid, isothiazole, and isovaleric acid were identified during thermal processing. 1-Octen-3-one content increased by 75 % from PP to PP + C + S through linolenic acid metabolism, which contributed to “cooked”; the formation of isobutyric and isovaleric acids, isothiazole, resulted in the enhancement of “sour/rancid” via serine and leucine metabolism.

Dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry (GC-MS) for the determination of soy sauce aroma compounds

In the present work, a dispersive liquid-liquid microextraction (DLLME) method combined with gas chromatography-mass spectrometry (GC-MS) was successfully developed for accurate determination of aroma-active components in soy sauce. Several key experimental parameters were optimized, including the type of dispersant, vortex time and the volume ratio of extractant and dispersant. The optimal conditions were 1200 μL acetone as dispersant, 800 μL dichloromethane as extractant and 3 min of vortex mixing. The proposed method was validated, achieving good linearities with R2 ≥ 0.9941, recoveries between 82 and 129% with 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) and 4-hydroxy-2 (or 5)-ethly-5 (or 2)-methyl-3(2H)-furanone (HEMF) within 84–103%, relative standard deviations ranging from 0.02 to 8.60% with HDMF and HEMF between 0.26 and 1.44%, and limits of detection and limits of quantification in the range of 0.08–35.95 μg/L and 0.25–119.83 μg/L, respectively. The entire sample processing with DLLME was completed in roughly 15 min with a total consumption of 2 mL of organic solvent, and 93 volatiles identified in the obtained extracts, with 87.1% (81 volatiles) showing relative standard deviations lower than 10%. Compared to conventional liquid-liquid extraction (LLE), DLLME exhibited obvious advantages of simplicity, rapidity, stability and low solvent consumption, favouring the extraction of acids and ketones. This is the first application of the DLLME technique for the analysis of aroma compounds in soy sauce and is suitable for rapid determination of key aroma compounds like HDMF and HEMF, especially for routine detection and large batch analysis of soy sauce, which can provide reliable information for soy sauce flavour analysis.

How anaerobic treatment is controlling the volatile components and key odorants of purple-colored leaf tea

Special purple-colored leaf tea products rich in γ-aminobutyric acid (GABA) have recently gained popularity. Although anaerobic treatment could effectively increase the GABA content in tea products, it also imparted an unknown unpleasant aroma. This study aimed to elucidate the dynamic effects of anaerobic treatment on volatile components during the purple-colored leaf tea processing and reveal the key aroma-active components. A total of 112 volatile components were identified, and it was found that anaerobic treatment could facilitate the accumulation of 2-heptanol, (E)− 2-hexenal, ethyl salicylate, phenylethyl alcohol, and (E,E)− 2,4-decadienal, but inhibited the formation of (Z)− 3-hexenyl acetate and methyl jasmonate. Moreover, 17 potent odorants including (E)-β-ionone, linalool, hexanal, 2-heptanol, (Z)− 3-nonen-1-ol, and (E,E)− 2,4-decadienal were distinguished as the key odorants of purple-colored leaf tea products rich in GABA based on gas chromatography–olfactometry and odor activity value analysis. These results provide new insights into the effect of anaerobic treatment on tea volatile metabolites.

Investigation on the changes of odor-active compounds of Amomum tsao-ko during natural drying

To characterize the key odorants in Amomum tsao-ko (AT) and to investigate their changes during natural drying, volatile compounds of AT were extracted and analyzed by solvent extraction combined with solvent-assisted flavor evaporation and gas chromatographymass spectrometry–olfactometry. A total of 41 aroma-active compounds with flavor dilution factors ranging from 3 to 6561 were identified in AT. Fourteen odorants were determined to be the key odorants by quantitation analyses, odor activity value (OAV) calculations, recombination and omission experiments. To further investigate the changes in aroma components in AT during natural drying, the concentrations and OAVs of odor-active compounds were measured at 0, 2, 4, 6, 8, 12, 16, and 20 days. The results showed that the number of aroma-active components did not change during natural drying, but their content changed with different trends. The concentration of geraniol showed a continuous upward trend; those of hexanal, octanal, nonanal and pinocarvone decreased first and then increased; those of α-pinene, sabinene, 2-nonanone, (E)-2-octenal, 2-nonanol, 4-terpineol, epidolichodial and (E,E)-2,4-dodecadienal changed on a fluctuating trend, while those of the other 28 compounds showed a trend of first increasing and then decreasing. These results provide a theoretical basis for further utilization of AT.

Characterization and Correlation of Dominant Microbiota and Flavor Development in Different Post-Mortem Processes of Beef.

Post-mortem aging could enhance the unique flavors of beef via several biochemical pathways. The microbiota is one of the important factors in the flavor development of aging beef, but their potential relationship has rarely been studied. This study characterized the apparent meat quality, flavor profiles, and microbial communities of beef during the different post-mortem processes, followed by the investigation of the correlations between the dominant microbiota and key volatile compounds. The results showed that wet-aged beef has a higher product yield and more stable color than dry-aged beef, as evidenced by the significantly lower value of aging loss and discoloration (ΔE). According to the odor activity value, 11 out of 65 compounds were categorized as aroma-active components, and 9 of them, including 1-pentanol, 1-octen-3-ol, hexanal, nonanal, heptanal, octanal, 2-nonenal, (E)-, 2-octenal, (E)- and 2-decenal, (E)-, were enriched in beef wet-aged for 7 d. Significant variances were found in the microbial communities of different aging beef. Of these, 20 microbiota (with 10 bacterial and 10 fungal genera) were recognized as the dominant genus. Partial least squares regression combined with a correlation network model revealed that five microbial genera, including Trichosporon, Prauserella, Rhodotorula, Malassezia, and Corynebacterium, constituted the functional microbiota responsible for flavor formation in aging beef and were positively associated with ≥7 key volatile compounds (p < 0.05, |ρ| > 0.7). This study suggests that the application of wet aging within 7 d on beef is better for meat quality and provides novel insights into the mechanisms of flavor formation in post-mortem aging beef via functional microbiota.

Evaluation of the differences between low-salt solid-state fermented soy sauce and high-salt diluted-state fermented soy sauce in China: from taste-active compounds and aroma-active compounds to sensory characteristics.

The present study aimed to determine the components related to sensory properties in soy sauce and to characterize the differences between low-salt solid-state fermented soy sauce (LSFSS) and high-salt diluted-state fermented soy sauce (HDFSS). The taste and aroma active components of 18 commercially available soy sauces (eight types of LSFSS and 10 types of HDFSS) were characterized. The relationship between these compounds, soy sauce samples, and sensory properties was modeled by partial least squares regression. The analysis showed that the 11 taste-active components, including glutamic acid, glycine, alanine, threonine, malic acid, citric acid, tartaric acid, acetic acid, lactic acid, reducing sugar and salt, contributed greatly to the taste of soy sauce. In addition, umami, saltiness and sweetness are the characteristic tastes of HDFSS, whereas sourness and bitterness were the characteristic tastes of LSFSS. At the same time, seven aroma-active compounds, namely 4-ethyl-2-methoxyphenol, ethanol, 3-methyl-1-butanol, ethyl acetate, 2-phenethyl alcohol, 3-methyl thiopropanol and 2-ethyl-4-hydroxy-5-methylfuran-3-one, played a decisive role in the flavor of soy sauce. In addition, HDFSS presented the aroma attributes of smoky, alcoholic, floral, fruity and caramel-like, whereas LSFSS mainly presented sour and malty aroma attributes. The present study reveals new insight into the relationship between the chemical composition and sensory characteristics of soy sauce, which is of great significance for developing an objective measurement system and providing a theoretical basis to improve the sensory quality of soy sauce. © 2023 Society of Chemical Industry.

Understanding the dynamic changes of volatile and non-volatile metabolites in black tea during processing by integrated volatolomics and UHPLC-HRMS analysis

Processing technology has an important effect on the flavor quality of black tea. However, the dynamic changes of volatile and non-volatile metabolites in black tea during processing are poorly understood. In this study, the volatile and non-volatile compounds during black tea processing were comprehensively characterized by integrated volatolomics and UHPLC-Q-Exactive/MS analysis. Volatile and non-volatile metabolites changed continuously throughout the processing process, especially during the withering stage. A total of 178 volatile metabolites and 103 non-volatile metabolites were identified. Among them, 11 volatile components with relative odor activity value greater than 1 (including dimethyl sulfide, 3-methylbutanal, 2-methylbutanal, β-myrcene, β-ocimene, linalool, methyl salicylate, β-cyclocitral, β-citral, citral, and β-ionone) were regarded as key aroma-active components responsible for finished black tea with sweet aroma. This study provides a comprehensive understanding of dynamic evolution trajectory of volatile and non-volatile metabolites during processing, which lays a theoretical foundation for the targeted processing of high-quality black tea.

The characteristic of the key aroma-active components in white tea using GC-TOF-MS and GC-olfactometry combined with sensory-directed flavor analysis.

White tea has become more and more popular with consumers due to its health benefits and unique flavor. However, the key aroma-active compounds of white tea during the aging process are still unclear. Thus, the key aroma-active compounds of white tea during the aging process were investigated using gas chromatography-time-of-flight-mass spectrometry (GC-TOF-MS) and gas chromatography-olfactometry (GC-O) combined with sensory-directed flavor analysis. A total of 127 volatile compounds were identified from white tea samples with different aging years by GC-TOF-MS. Fifty-eight aroma-active compounds were then determined by GC-O, and 19 of them were further selected as the key aroma-active compounds based on modified frequency (MF) and odor activity value (OAV). Aroma recombination and omission testing confirmed that 1-octen-3-ol, linalool, phenethyl alcohol, geraniol, (E)-β-ionone, α-ionone, hexanal, phenylacetaldehyde, nonanal, (E, Z)-(2,6)-nonadienal, safranal, γ-nonalactone and 2-amylfuran were the common key aroma-active compounds to all samples. Cedrol, linalool oxide II and methyl salicylate were confirmed peculiar in new white tea, while β-damascenone and jasmone were peculiar in aged white tea. This work will offer support for further studies on the material basis of flavor formation of white tea. © 2023 Society of Chemical Industry.

Volatile profiles and aroma-active components of Northern Thai fermented soybean (thua nao) produced from controlled and uncontrolled fermentations

Thua nao is a fermented soybean product that is widely consumed, especially in the northern part of Thailand. Thua nao can be used as a condiment to enhance the aroma and flavor of foods. In general, commercial thua nao is traditionally made by indigenous microbial, especially Bacillus spp. fermentation under ambient conditions, leading to inconsistencies in product aroma quality. To solve this problem, inoculation of selected microorganisms can help control thua nao consistency. The objective of this research was to characterize and compare volatile aroma-active compounds in three samples, including thua nao made by commercial Bacillus subtilis inoculation fermented under controlled conditions (YSB) and two thua nao products made by indigenous fermentation in commercial production sites in Lumpoon (LPN) and Chiang-Mai (CMI) provinces, Thailand. It was found that 2-methyl butanoic acid, phenylethyl alcohol, benzaldehyde, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine and 2-methoxy phenol were dominant compounds in the YSB samples. These compounds contributed to fermented/sour, floral, almond-like and nutty aromas, which were related to positive attributes perceived by consumers. In contrast, several aldehydes and ketones related to off-aroma as oxidized, fatty, green, and earthy attributes derived from lipid oxidations were dominantly detected in samples from uncontrolled fermentations (LPN and CMI). From the study, it can be implied that inoculation of B. subtilis in thua nao fermentation could enhance aroma compounds with positive attributes and thus improve the organoleptic property of the product. These findings could benefit fermented soybean manufacturers to improve their aroma quality and to control products’ consistency by controlling fermentation conditions.

Effects of Drying Methods on Taste Components and Flavor Characterization of Cordyceps militaris.

The influences of four drying methods (hot air drying (HAD), vacuum freeze drying (VFD), vacuum drying (VD) and intermittent microwave combined with hot air drying (MW-HAD)) on the taste profile and flavor characteristic of Cordyceps militaris were investigated. MW-HAD samples had the highest levels of umami taste 5'-nucleotides, bitter taste amino acids, and equivalent umami concentration (EUC) value. The aroma fingerprints and differences of dried Cordyceps militaris were established by GC-MS with odor activity values (OAVs) and GC-IMS with principal component analysis (PCA). GC-MS data showed that the predominant volatiles of dried samples were aldehydes, alcohols, and ketones. VFD samples had the highest amount of total aroma compounds and C8 compounds. Moreover, 21 aroma-active components (OAVs ≥ 1) were the main contributors to the flavor of dried Cordyceps militaris. The OAVs of 1-octen-3-one and 3-octanone associated with mushroom-like odor in VFD were significantly higher than other samples. Furthermore, a significant difference in flavor compounds of four dried samples was also clearly demonstrated by GC-IMS analysis with PCA. GC-IMS analysis revealed that VFD samples had the most abundant flavor compounds. Overall, MW-HAD was an effective drying method to promote umami taste, and VFD could superiorly preserve volatiles and characteristic aroma compounds in dried Cordyceps militaris.

Volatiles in Berries: Biosynthesis, Composition, Bioavailability, and Health Benefits

Volatile compounds in fruits are responsible for their aroma. Among fruits, berries contain many volatile compounds, mainly esters, alcohols, terpenoids, aldehydes, ketones, and lactones. Studies for volatile compounds in berries have increased extensively as the consumption of berry products rapidly increased. In this paper, we reviewed biosynthesis and profiles of volatiles in some berries (strawberry, blueberry, raspberry, blackberry, and cranberry) and their bioavailability and health benefits, including anti-inflammatory, anti-cancer, anti-obesity, and anti-diabetic effects in vitro and in vivo. Each berry had different major volatiles, but monoterpene had an important role in all berries as aroma-active components. Volatile compounds were nonpolar and hydrophobic and rapidly absorbed and eliminated from our body after administration. Among them, monoterpenes, including linalool, limonene, and geraniol, showed many health benefits against inflammation, cancer, obesity, and diabetes in vitro and in vivo. More research on the health benefits of volatile compounds from berries and their bioavailability would be needed to confirm the bioactivities of berry volatiles.

Determination of the Physicochemical Properties and Fatty Acid Composition of Some Cheese Types with Geographical Indication in Thrace Region

The purpose of the present investigation was to assess the differences in the quality characteristics of the famous cheese types produced in Thrace region and labeled with a geographical indication or not. The different physicochemical properties, mineral content, and fatty acid composition of Ezine Cheese and Edirne Feta Cheese, and Malkara Aged Kaşar Cheese with geographical indication were determined. The obtained data were compared with some of the physicochemical specifications stated in the geographical indication registration documents and also with the cheese types of the same category but without the geographical indication. For this purpose, 90 cheese samples from 23 different local producers in Edirne, Tekirdağ, Çanakkale, and Kırklareli were supplied in sealed packages. Dry matter (%), ash (%), salt (%), protein (%), titratable acidity (% lactic acid), acid count (mg KOH/g fat), color (L, a, b) values were determined. Additionally, fatty acid compositions and some mineral contents of the cheese were analyzed by using gas-chromatography and inductively coupled plasma-optic emission spectrometry (ICP-OES). This study aims to contribute to registration documents of geographical indication, which cover the characteristic specifications, including fatty acid composition, protein amount, acid count (free fat acidity), and color (L*, a*, b*) values. It is advised to revise the registration documents of the mentioned cheese types by including aroma-active components to the aroma characterization and texture specifications to the characteristic features through a broader study.

Identification of aroma-active compounds responsible for the floral and sweet odors of Congou black teas using gas chromatography-mass spectrometry/olfactometry, odor activity value, and chemometrics.

Floral and sweet odors are two typical characteristic aromas of Congou black tea, but their aroma-active compounds are still unclear. Characterizing the key aroma-active compounds can provide a theoretical foundation for the practical aroma quality evaluation of Congou black tea and directional processing technology of high-quality black tea with floral or sweet odors. Gas chromatography-olfactometry (GC-O) combined with odor activity value (OAV) is often used to screen key aroma-active substances, but the interaction between aroma components and their impact on the overall sensory quality is ignored. Therefore, in this study, OAV combined with variable importance in projection (VIP) and Spearman correlation analysis (SCA) were used to characterize the aroma-active components of Congou black teas with floral and sweet odors. Eighty-five volatiles were identified in these samples using gas chromatography-mass spectrometry (GC-MS). Twenty-three compounds were identified as potential markers for the floral and sweet odors of Congou black teas from orthogonal partial least squares discriminant analysis (OPLS-DA). Eighteen compounds were selected as candidate aroma compounds based on GC-O analysis and OAV calculations. In addition, 26 compounds were screened as crucial aroma compounds based on SCA. Finally, 19 compounds were evaluated as key aroma compounds by the comprehensive evaluation of VIP, OAV, and SCA. Terpenoids are the main active compounds that contribute to the floral odor of Congou black tea, whereas aldehydes are the key compounds for the sweet odor. The proposed method can effectively screen the aroma-active compounds and can be used for comprehensive quality control of products. © 2022 Society of Chemical Industry.

Characterization of aroma active volatile components in roasted mullet roe

Mullet roe is a popular global delicacy that derives its unique roasted flavor from several odors, including savory, rich, salty, and fishy attributes. Despite the nutritional significance of mullet roe, studies on their volatile components are yet to be reported. Headspace-solid-phase microextraction coupled with gas chromatography–olfactometry and aroma extract dilution analysis was applied to determine the volatile components of roasted mullet roe. Analysis of roasting time and temperature revealed that both are important parameters on aroma generation. Volatiles, including acetic acid, methional, hexanoic acid, and benzeneacetaldehyde were identified as the most potent odorants of raw mullet roe, while 2-ethyl-5-methylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 5-methyl-2-phenyl-2-hexenal, and sulfurol were the primary odorants in roasted mullet roe. Reaction models using the water extract and defatted residue had the most similar flavor profile to that of roasted mullet roe, with Maillard reaction as the key flavor generator in roasted mullet roe.

Identification of aroma-active components in black teas produced by six Chinese tea cultivars in high-latitude region by GC–MS and GC–O analysis

Identification of aroma-active components in black teas produced by six Chinese tea cultivars in high-latitude region by GC–MS and GC–O analysis

Sensory-Based Identification of Aroma-Active Compounds in Hotpot Seasoning before and after Boiling.

Boiling, the most frequent edible way to hotpot seasoning (HS), exerts a significant impact on the aroma of HS. The present study employed, for the first time, a novel switchable system between GC-O-MS and GC×GC-O-MS (SGC/GC×GC-O-MS) to study the aroma compounds of HS and hotpot seasoning boiling liquid (HSBL). A total of 79 aroma compounds and 56 aroma-active compounds were identified. The aroma extract dilution analysis (AEDA) was used to analyze the differences between the key aroma-active components in the HS and HSBL. The results showed that 13 aroma-active components were significantly affected by boiling, such as D-limonene, methional, and linalool. Moreover, a total of 22 key aroma-active components were identified through the odor activity values (OAVs) calculation. Of them, (E)-2-octenal (fatty) and linalool showed a significant difference, suggesting them to be the most critical aroma-active compounds in the HSBL, and HS, respectively. Finally, the correlation between key aroma-active compounds and the sensory properties of HS and HSBL was studied. These results demonstrated that the OAVs of key aroma-active compounds could characterize the real information of samples through bidirectional orthogonal partial least squares (O2PLS). The analysis results were consistent with the sensory evaluation results.

Characterization of Key Aroma Compounds in Tartary Buckwheat (Fagopyrum tataricum Gaertn.) by Means of Sensory-Directed Flavor Analysis

The key odorants of tartary buckwheat (TB) were researched by a sensory-directed flavor analysis approach for the first time. After the volatiles of TB were isolated by solvent-assisted flavor evaporation (SAFE), 49 aroma-active components with flavor dilution (FD) factors in the range of 1-2187 were identified using gas chromatography-olfactometry-mass spectrometry (GC-O-MS) combined with aroma extract dilution analysis (AEDA). Geranylacetone, phenethyl alcohol, and β-damascone showed the highest FD factors of 2187. All 49 odorants were further quantitated by the internal standard curve method, and their odor activity values (OAVs) were obtained. The overall aroma of TB was successfully simulated (similarity > 98.16%) by mixing 16 odorants (OAV ≥ 1) with their natural concentrations. The omission tests revealed that geosmin, α-isomethylionone, α-methylionone, β-ionone, linalool, β-damascone, geranylacetone, guaiacol, ethyl hexanoate, geraniol, vanillin, tetrahydrolinalool, and 2,5-dimethyl-4-hydroxy-3-(2H)-furanone were the key odorants of TB. Chiral analysis showed that tetrahydrolinalool and linalool existed as racemics in the commercial TB. The relative content of R-enantiomers of α-isomethylionone and α-methylionone was slightly higher than that of their S-enantiomers. The odor thresholds of R- and S-enantiomer of tetrahydrolinalool were first detected as 0.029 and 3.8 μg/L in air, respectively.